Study On Photosynthetic Physiological Characteristics And Tissue Culture Technology Of Mutant Malus Spectabilis

Malus spectabilis is a deciduous shrub or small tree of the Genus Rosaceae,because the mutant leaves not only the leaves turn from purple to green,but also the purple color at the beginning of the fruit,and the color of the autumn is from purple to red,meaning that a riot of colour,compared with normal Malus spectabilis,which not only increases the diversity of color changes,satisfies people's requirements for new,special and strange ornamental plants,but also extends the viewing period to a certain extent.Therefore,Malus spectabilis mutant plants with this specificity will be more popular in the market in the future.For the traits of mutant plants,it needs to be preserved by tissue culture.However,some plants have weaker growth and are reflected in photosynthesis.Therefore,for the Malus spectabilis mutant plants,the photosynthesis of the Malus spectabilis can be estimated.Whether the seedlings can grow normally,if the photosynthetic capacity of the mutant plants is not lower than that of the normal plants,then the expansion of the Malus spectabilis mutant plants is carried out by means of tissue culture.If the photosynthetic capacity of the Malus spectabilis mutant plants is weaker than the normal Malus spectabilis the tissue culture is meaningless.Therefore,the paper first measured the photosynthesis rate of the comparatively mutated plants and normal Malus spectabilis,followed by tissue culture studies.In this study,we studied the analysis of photosynthetic physiological characteristics of mutant Malus spectabilis and tissue culture expansion technology,and reached the following conclusions:?1?Through the photosynthetic gas exchange parameters experiments,it was found that in April,the diurnal variation of the net photosynthetic rate of normal and mutant Malus spectabilis showed a double-peak curve,with a peak at around 12:00,a secondary peak around 16:00,and“a photosynthetic midday depression”caused by non-stomatal limiting factors Phenomenon;The Pn value of mutant Malus spectabilis is larger than the normal Malus spectabilis at each point,indicating that its utility rate of luminous energy is higher than that of normal Malus spectabilis.?2?Through the chlorophyll fluorescence experiments,it was found that the fluorescence parameters of mutant Malus spectabilis and normal Malus spectabilis were different in different seasons,mainly reflected in the spring and summer mutant Malus spectabilis F_v/F_m,?PSII,qP,ETR and other values were larger than normal Malus spectabilis.;the values of?PSII,qP,F_v/F_m,and ETR in autumn mutant Malus spectabilis are lower than normal Malus spectabilis.Therefore,by comparing the photosynthesis and fluorescence parameters of mutant Malus spectabilis and normal Malus spectabilis,The photosynthetic capacity of mutant Malus spectabilis in spring and summer was better than that of normal Malus spectabilis,but the autumn was slightly worse.It can be seen that the mutant Malus spectabilis tissue culture seedlings can grow normally in the late stage,and it is observed that the mutant leaves fall off.Earlier,it can be seen that mutant Malus spectabilis matures earlier and leaves earlier,and this characteristic prolongs the fruit viewing period and has more ornamental value.Therefore,it can maintain its specificity through tissue culture research.?3?Through the screening and disinfection research of explants experiments,it was found that the best disinfection method for the bud stem segment is 0.05%mercury chloride 20 min;the callus differentiation formed by the petiole of the mutant Malus spectabilis is difficult,and the leaf differentiation rate is not high,so the stem segment is selected as The explants are subjected to bud induction culture,and this method is an ideal cultivation method for the tissue culture of the mutant Malus spectabilis?4?Through the culture studies by adventitious bud induction,it was found that mutant Malus spectabilis was optimally disinfected,and the unpolluted and surviving single bud stem segments were used as test materials after disinfection.The three-factor and three-level orthogonal test design was used to select medium,6-BA,NAA.For the experimental factors,the starting rate of different treatments was counted after 30 days,and the optimal medium and hormone combination for the induction of adventitious buds in the stem segments of mutant Malus spectabilis were screened out,ie MS+6-BA 2.0 mg/L+NAA 0.2 mg/L.?5?Through the bud generation and proliferation culture research,it was found that the adventitious buds were inoculated as subculture materials,and the orthogonal test design of two factors and three levels was adopted.MS was used as the basic medium,and 6-BA and IBA were used as experimental factors.After 30 days,the buds were observed.The growth rate,record its proliferation coefficient,and carry out range analysis and analysis of variance,and then screen out the best hormone combination for the propagation of mutant Malus spectabilis buds.The optimal level combination of the proliferation of mutant Malus spectabilis buds is MS+6-BA 2.5mg/L+IBA 0.3 mg/L.?6?Induction of rooting culture by tissue culture seedlings,it was found that1/2MS was used as the basic medium and IBA and NAA were added as the rooting medium.The average root number and root morphology analysis showed that the average root number of 0.5mg/L IBA was higher and the rooting was best.Therefore,the best rooting medium was 1/2MS+0.5mg/L IBA.?7?Through the research on the cultivation and transplanting of tissue culture seedlings,it was found that different transplanting substrates have a greater impact on the survival rate of transplanting.Taking 3/5 campus forest soil+2/5 vermiculite as the substrate,the survival rate of tissue culture seedlings was the highest,which could reach 86.67%,and the transplanted seedling grows robustly.Therefore,3/5 campus forest soil+2/5 vermiculite is the most suitable transplanting substrate for mutant Malus spectabilis tissue culture seedlings.